Despite the prevalence of working memory deficits following traumatic brain injury (TBI), the scientific data regarding pharmacological treatment of this problem is limited. As deficits in working memory are known to have a significant impact on functional outcomes for individuals with TBI, further research in this area is essential. The primary goal of the proposed project is to examine the efficacy of CDP Choline in the treatment of working memory deficits following TBI. The study sample will consist of 48 subjects including a group of 24 individuals who have sustained moderate to severe TBI and a group of 24 healthy controls. Each group will be divided into a placebo and treatment group. The project will utilize functional Magnetic Resonance Imaging (fMRI) to investigate the cerebral neurophysiological effects of treatment with the drug of choice. A working memory task will be employed during the fMRI sessions. The effects of treatment with CDP Choline will be evaluated on neuropsychological testing performance also and correlations between behavioral performance and neuroimaging results will be observed. Results will be compared pre and post test or one month after treatment. The study postulates the following assumptions: 1) Baseline fMRI results will show altered patterns of cerebral activation for persons with TBI compared to normals;2)With treatment, TBI subjects will display fMRI patterns that more resemble healthy controls;3) Improvements in behavioral performance on both neuropsychological tests and the working memory task will be associated with treatment, with greater changes in the TBI group comparisons.;4) correlations between neuropsychological tests and neuroimaging results will be stronger for persons with TBI as compared to placebo/control groups.